
/*
 * Copyright © Stéphane Raimbault <stephane.raimbault@gmail.com>
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include <iostream>
#include <stdio.h>
#ifndef _MSC_VER
#include <unistd.h>
#endif
#include <errno.h>
#include <stdlib.h>

#include <modbus/modbus.h>

int main(void)
{
    int s = -1;
    modbus_t *ctx;
    modbus_mapping_t *mb_mapping;

    ctx = modbus_new_tcp("192.168.1.44", 1502);
    modbus_set_debug(ctx, TRUE);

    // 分配四个数组来存储输出线圈，输入线圈，输入寄存器，保持寄存器, 指针存储在mb_mapping结构中
    mb_mapping = modbus_mapping_new(500, 500, 500, 500);
    if (mb_mapping == NULL)
    {
        fprintf(stderr, "Failed to allocate the mapping: %s\n", modbus_strerror(errno));
        modbus_free(ctx);
        return -1;
    }

    //等待连接请求
    s = modbus_tcp_listen(ctx, 1);
    //允许连接
    modbus_tcp_accept(ctx, &s);

    for (;;)
    {
        uint8_t query[MODBUS_TCP_MAX_ADU_LENGTH];
        //从ctx环境接收请求，并将指示请求存储到query中,返回请求的队列长度;
        int rc = modbus_receive(ctx, query);
        if (rc > 0)
        {
            /* rc is the query size */
            //响应请求，并在mb_mapping映射中执行;
            modbus_reply(ctx, query, rc, mb_mapping);
        }
        else if (rc == -1)
        {
            /* Connection closed by the client or error */
            std::cout << "aaaaaaaaaaaaaaaaaaaa" << std::endl;
            break;
        }
    }

    printf("Quit the loop: %s\n", modbus_strerror(errno));

    if (s != -1)
    {
        close(s);
    }
    modbus_mapping_free(mb_mapping);
    modbus_close(ctx);
    modbus_free(ctx);

    return 0;
}